Screening of Endophytic Bacteria from Organic Rice Tissue for Indole Acetic Acid Production

The objectives of this study were to isolate and characterize endophytic bacteria from various rice tissues focusing on their ability to produce indole acetic acid (IAA). Rice tissue samples were collected from different three types of rice farm; 1 year, 3 years organic rice, and conventional rice farms in Udon Thani, Thailand. Seventy-one isolates of endophytic bacteria were screened using PDA and TSA medium. The majority of strains isolated from root tissues were totally 26 isolates, exclusively collected from 3 years organic rice farm. Phenotypic characteristics of all isolates illustrated that 34 isolates were identified as Pesudomonas sp., while other isolates were also identified as Bacillus, Azotobacter, and Enterobacter species. The study of IAA production indicated that 4 isolates efficiently produced IAA over than 10 μg/ml. The O-1-R-4 (2) isolate produced the highest IAA (14.58 μg/ml), and it was identified as Bacillus sp. This effective result will be used for further investigation on the feasibility of commercial production of IAA up-scale fermentation.